For the most part, the field to replace retiring Sen. Mel Martinez (R-Fla.) has been slow to develop.

Two of the most popular figures in Florida politics — former Gov. Jeb Bush (R) and Chief Financial Officer Alex Sink (D) — decided not to run. Rep. Allen Boyd (D-Fla.) also decided against a bid. Gov. Charlie Crist (R) is seriously considering jumping in but won’t make any announcement until May, at the earliest.

Even the candidates who have announced they’re running in 2010 haven’t made much noise. State Sen. Dan Gelber (D) has been focused on the state’s legislative session. Former state House Speaker Marco Rubio (R) formed an exploratory committee last week but made no formal announcement.

Then there is Rep. Kendrick B. Meek (D-Fla.).

The first candidate to announce for the seat in January, the four-term congressman is already in full campaign mode. He’s been busy raising money, working the rubber chicken circuit and courting elected officials and potential supporters from Jacksonville to Miami. He’s also hiring top-notch campaign staff in an effort to get a head start.

Though the election is still 20 months away, he has held two fundraisers with former President Bill Clinton, netting his campaign around $390,000. And he also won two key endorsements — from the Service Employees International Union and from the largest teachers union in the state.

Meek began the year with $428,000 in his campaign account.

“The challenge he has is getting known statewide,” said Florida Democratic consultant Dave Beattie. “What he’s doing is using the one resource that decreases over time — and that’s time. You can never get more time, so he’s maximizing the time he has now before the election to raise money and build a volunteer base.”

His frenetic — and early — campaign activity belies his experience as a pol who has never had to exert much effort to win in his heavily Democratic, Miami-Dade and Broward County-based House district. Even when he first ran for the open seat in 2002, he skated into office without primary or general election opposition, a gift from his mother, former Rep. Carrie Meek, whose unexpected and suspiciously timed retirement announcement left almost no chance for opposition to develop.

Meek has run unopposed in every primary and general election since then, except for a 2006 primary, when he won with 87 percent of the vote. The district, which has the lowest number of registered Republicans in the state, gave more than 80 percent of the vote to Barack Obama.

“The reason I haven’t had a lot of opponents is because I’ve always worked hard,” said Meek. “I’m now pulling double shift as a congressman and as a candidate. ... People should not underestimate my work ethic.”

But since Meek has never had to run in a competitive congressional race, he was forced to start from scratch when building his Senate campaign infrastructure. In a sign of the seriousness of his effort, Meek hired Obama’s deputy campaign manager, Steve Hildebrand, to run his campaign.

In the House, Meek quickly made a name for himself in his three terms, and he is one of only two Floridians on the Ways and Means Committee — a plum assignment because of the vast fundraising opportunities it affords committee members. He’s a favorite of House Speaker Nancy Pelosi, who tapped him in 2004 to be co-chairman of the 30-Something Working Group to engage younger voters.

Political consultants, though, warn that Meek faces considerable challenges in broadening his appeal beyond his urban, South Florida base.

“One of the challenges in Florida is it’s very hard to win statewide if the entirety of your political story is written in one of the southern urban counties,” said Steve Schale, who ran Obama’s campaign in Florida and is now working for Gelber.

“The road map to winning Florida is not about expanding the base, but it’s about winning on the I-4 corridor.”

Of course, Meek isn’t the only Democratic contender who lacks statewide recognition — Gelber is also virtually unknown throughout the state. And unlike Meek, Gelber has been occupied with his legislative duties and has spent less time ramping up for the campaign.

The wild card for Florida Democrats is Tampa Mayor Pamela Iorio, who has been exploring a campaign. She hails from the most politically competitive part of the state, but she isn’t plugged into the party establishment and, like Meek, she has little experience running the kind of rough-and-tumble campaign that will most likely be necessary to win the seat.

“All the candidates are regional candidates so far, but Meek’s done better at trying to expand his base so far,” said Susan MacManus, a political science professor at the University of South Florida.

“But the bottom line is he still hasn’t run a statewide race, and people who are successful at statewide races tell you it’s a whole different ballgame when you run statewide.”

The racial dynamic will also play a key role in the campaign. Meek has a natural base of support among African-Americans, who make up about one-quarter of the Democratic primary vote. Expanding African-American turnout in the primary will be crucial to his success, but he’ll also need to expand his appeal among white voters.

“There are a lot of minority candidates all over the country who have won without being part of the majority population. Race has become much less of a factor in recent years,” said Hildebrand.

“He needs to grow his strength in the I-4 corridor and the northern part of the state, two places where he’s not as well known in Florida.”

On the Republican side, all eyes are on Crist. Rubio has said he is likely to run for governor if Crist enters the race. GOP Reps. Connie Mack and Vern Buchanan have expressed interest but also are awaiting Crist’s decision.

Florida’s primary isn’t until late August 2010, and candidates need not file until May 2010.

“With the exception of Crist, all of these guys are going to have to expand their base significantly,” said Schale. “Dan [Gelber] says he’s not even a household name in his own household.”